I see many homes in our humid Florida that have a grungy black stain on their roofs, eaves, and walls. There are several companies that would love to remove this black crud for a few hundred dollars with their power washers - that high price is probably why the homes stay black with the crud, Most people just do not know it can be removed with a $5 gallon of bleach. I had some build up of this black crud on my gutters and eaves even though the house is 3 years old. The photo above shows the tools needed besides the gallon of bleach. A sprayer designed to handle the caustic effects of bleach can be purchased at the hardware store of your choice. Water - the bleach should be diluted with water to a 50/50 mix for tough stains or 25% bleach to 75% water for more mild crud. A ladder - to get close to the area to be sprayed so the nozzle of the sprayer can just mist on the cleaning solution. Which brings up the hose - spray all your plants and ground level areas to keep them wet and so they will not be damaged by the spraying above (I found the misting technique lessens the dripping). In the photo is also my protection - gloves and goggles to go with the clothes you will be wearing. Cover up your skin with old clothes that you do not care if they get bleached from errant drops of bleach water. When all the ground areas and plants have been soaked you are set to go - just mist on the solution and the crud will disappear and leave your home looking new again. No need to rinse. The other areas that you can't reach with a ladder and the mist technique will require the spray wand nozzle being turned to spray or stream - which uses a lot more solution and can be messy - just have your hose handy to wet down any over spray.